1. Field of the Invention
The invention generally relates to connection re-establishment procedures and, more particularly, to an apparatus and method for a radio resource control (RRC) protocol to re-establish connection in a radio network system environment.
2. Description of the Related Art
A universal mobile telecommunications system (UMTS) is a third generation mobile communication system that has evolved from the Global System for Mobile communications (GSM) system. The UMTS is a European standard which aims to provide better mobile communication services based on the GSM core network and wideband code division multiple access (W-CDMA) technology. Although UMTS delivers high data transfer rates, wireless data usage is expected to increase significantly over the next few years. For this reason, concepts for UMTS Long Term Evolution (LTE) have been proposed and the objective is to further improve UMTS to achieve high-data-rates, low-latency and packet-optimized radio access technology. The improved UMTS is called Evolved Universal Terrestrial Radio Access (E-UTRA).
Consider a wireless mobile device, generally referred to as a user equipment (UE), which complies with the 3GPP specifications for the E-UTRA protocol. The 3GPP TS 36.331 specification, v.8.2.0, with the accepted change request R2-083795, referred to herein as the 36.331 specification, addresses the subject of the E-UTRA RRC (Radio Resource Control) protocol requirements between the E-UTRA Terrestrial Radio Access Network (E-UTRAN) and the UE.
In accordance with clause 5.3.7.2 of the 36.331 specification, the UE shall initiate the RRC protocol connection re-establishment procedure whenever the “Radio Link Control (RLC) protocol indicates that the maximum number of re-transmissions has been reached”. It further recites that the UE shall only initiate the procedure when security has been activated. However, there may be a situation where the RRC protocol security mode has not yet been activated when the RLC protocol indicates that the maximum number of re-transmission has been reached.
The above situation is described in the 3GPP TS 36.322 specification, v.8.2.0. The RLC indicates that the maximum number of re-transmissions has been reached when the RB (radio bearer) is mapped on a RLC AM (acknowledged mode). However, the default configuration of the SRB1 (signaling radio bearer 1) is mapped on a RLC AM as specified in the 36.331 specification and the configuration messages for activating the RRC security mode are expected to be transmitted on the SRB1. Thus, the RRC security mode may not be activated when the RLC indicates that the maximum number of re-transmissions has been reached. This results in contradiction to the precondition that the UE can only initiate the RRC protocol connection re-establishment procedure when the RRC security mode has been activated, and may further cause the UE operational errors.